Added a coolant filter
 

I did a pretty in-depth tear apart/repair of the cooling system in the ZJ I bought 20 years old. Didn't know much about its history and it had developed a leak, so I figured it was a good time to make sure everything was in good shape (it wasn't.)

I decided to experiment with putting a coolant filter in. I know some larger diesel engines use them, and some commercial trucks. Probably minimal benefit for us, but I was curious. I installed this inline with the heater return hose. Stock heater hoses will work fine, but I replaced mine.

Parts:

• 1x Filter Mounting Base w/ 11/16"-16 threading for filter
• --
  I think this is the same thing, but half the price and without the bracket that I didn't end up using
  I think this is the same thing, but half the price and without the bracket that I didn't end up using
• 1x Coolant Filter
  1x Coolant Filter
• 5' of 5/8" ID Silicone Tubing
  5' of 5/8" ID Silicone Tubing
• --This had reinforcement braiding, even though the picture doesn't show it
• 3x 3/8" MNPT x beaded barb fittings
• --2 were for the filter mount and one to replace that obnoxious heater return tube that can't removed without removing the entire pump, and can't be tightened in any case...
• 24 mm Constant-Tension Hose Clamps

The filter can't handle anything close to the flow rate you want, so I drilled a 3/16" bypass hole to allow higher flow rates and continued flow if the filter ever becomes completely blocked. I might expand that if I'm not happy with the heater performance.

Here are some pictures of the filter project, and a couple others from the other work done. The filter is just hanging there for now - I'm making a mount that will attach just behind the hood.


https://cimg0.ibsrv.net/gimg/www.che...0ad667a1f7.jpg



https://cimg1.ibsrv.net/gimg/www.che...ab794f9ae6.jpg

https://cimg3.ibsrv.net/gimg/www.che...43d4c4d5a3.jpg

https://cimg5.ibsrv.net/gimg/www.che...284af552a8.jpg

https://cimg6.ibsrv.net/gimg/www.che...10b1588e3b.jpg

https://cimg8.ibsrv.net/gimg/www.che...11abea5557.jpg

https://cimg3.ibsrv.net/gimg/www.che...9d466d9f6a.jpg

Looks pretty cool but I am curious how it will be in near 100 degree heat in the summer and if there is still enough flow.

I don't get this whole thing about coolant filters. If you maintain your cooling system properly and flush it properly you should never have any debris to worry about.

It should actually increase cooling of the engine. On the 4.0, coolant is always flowing through the heater lines and core, the thermostat only controls flow through the radiator. Additional restriction in the heater loop should increase flow through the radiator, at the expense of some cabin heating capability.
I think I made the bypass hole big enough that the drop in cabin heating shouldn't be very noticeable, but I can always drill it out a bit more if need be!

Well, I wouldn't say they offer a whole lot of benefit. I did mine out of curiosity rather than a perceived necessity.

Still, I wouldn't say they are useless. I'd be surprised if they didn't extend water pump life, improve coolant performance during its recommended life, and help keep heat transfer levels high. Plus, if for some reason you do have... whatever entering your cooling system, they'll hopefully get rid of it.

I'm open to having my mind changed though! I'll also update whenever I decide to change the filter and cut the old one open.

There is more science to it than just filtration. This has now become a standard on big rig motors. There are filters with time release anti-corrosion additives and even some with sacrificial anodes like marine engines have built into the filter. It's actually not a bad idea at all because when serviced regularly you will get absolutely ZERO corrosion and ZERO calcium deposits in your system, and I mean zero.

With the right filter choices you just did one of the best things you could have done to your engine man. Seriously...

https://www.donaldson.com/en-us/engi...ducts/coolant/

That's interesting. I specifically avoided a filter with any additives since I wanted to do a little more research on what they contain. Might go with one of those for the next one though, especially if I ever do a more thorough removal of existing deposits of the block!

Absolutely... Like I say they are time release, and the sacrificial anode works just like they do in marine applications. And because of the engine and cooling system costs in the heavy truck industry this has become a standard with most manufacturers.

It works... :)

i think you are right on that one. do you think the cooling will be significantly better if the heater core flow is cut off?

If you mean cut off completely, I'd worry about that since I don't think you'd get much circulation through the block until the thermostat opened up, and its opening would be delayed anyway by that lack of circulation. There is usually some small initial flow through a thermostat, but I *think* it would be insignificant in this scenario.

In regard to being partially cut off... On one hand you have a smaller coolant volume available to help dampen the effect of short-term high heat generation. Plus, I'd guess an increase in work required to spin the water pump with the increased flow restriction.
On the other hand you have faster coolant flow through the radiator. This seems to be a controversial topic, but as I understand it, greater flow on the scales we are concerned with means greater cooling rate. The OEM pump doesn't seem to be very good at overcoming flow restriction though, and I'd guess this increase in flow through the radiator via restricting the heater would be more significant with a pump that could build higher pressures.

I also wouldn't expect any if this to come into play in any way that matters until after the thermostat has fully opened. If that is the case though, and just throwing out numbers, a 3-5% increase in cooling capacity wouldn't surprise me.

Faster flow doesn't always equate to better cooling. Sometimes it can flow so fast it isn't in the radiator long enough to cool as it should. If I were doing this myself, I would look at the filter adapter housing to see if the passages could be drilled bigger for more flow through the heater core and filter. The filter will handle an increased flow with no problem until it starts to get plugged up. At which point it would probable be due for a change and service anyways. :)

Great, now I'm gonna have to get a flow meter and a couple temperature gauges haha. Anyone have ideas for these that would be able to be fitted close to the radiator inlet and outlet? I'll do some testing!

Lol... I don't think you have to go to all that trouble unless you absolutely have to prove a theory. I would just see if if can be drilled out to 3/8 ths to a 1/2 inch without destroying the housing and go with that.

1/2 inch is enough to let a 1000 fpm of air or a few hundred gallons of liquid per minute to flow without much restriction so it should be plenty. :)

I'm just curious, and enjoy these project when I have the time for them.

As far as the housing though, 1/2" would definitely not compromise the housing, and that + the filter flow would probably just just barely under original flow rates.

Just remember your geometry, gentlemen. Any increase in diameter increases flow by a factor of 4, as in area of the circle.

Yep, a lot of early cars only had 1/2 heater hoses and worked fine.

Is that what the ratio is? That's good math to have for the future. :)

Hey... Happy birthday Dave. Somehow I missed that until just as I was running out the door last night. :)

Thanks, Bugout!

If you make the bypass hole 1/2" you will rob all the flow thru the filter. I wouldn't make the bypass hole larger than 1/4". Remember pressure is controlled by the rad cap and the pump just provides flow. In other words, you can have zero flow and still only have 18 psi pressure, until the coolant gets hot enough to produce steam. Steam expands exponentially and pressure increases rapidly. That's why air pockets are so dangerous. They create places for steam pockets to form.

Lets just assume for the sake of discussion that the flow rate thru the filter and 1/4" bypass hole are the same. As the filter picks up debris, the flow rate decreases and the velocity of the flow thru the bypass hole increases. Pressure will remain the same. Also remember that the water pump is a submerged centrifugal pump and doesn't add pressure, it only provides flow.

Until the thermostat opens, 99.9% of the water pump flow goes thru the heater core. After it opens, very little flow goes thru it. It still gets system pressure. A good thermostat acts like a throttle valve controlling system temperature, opening and closing gradually.

OK I need to find out if I have confused myself on this. I was under the impression he had installed the filter inline to or from the heater core. Is there a bypass port in that housing? If so I agree this doesn't need to be very big. I thought we were talking about the normal line passages through the filter needing to be larger for more flow through the heater core?

Have I mixed myself up here??? lol

He drilled a 3/16" bypass hole on the filter housing.

Sorry, but I just woke up after trying it catch some sleep for work tonight and my mind isn't quite clear yet. It's been a while since I've done any hydraulics work, but the flow is controlled by the smallest orifice in the system, that being the inside of the barb connectors for the hoses, forgetting about the filter and the bypass hole. There will be a slight pressure drop after any orifice that restricts flow, but it's negligible compared to flow drop.

Most of my work was with positive displacement pumps and pressure control valves. Working with a centrifugal pump is another ball game because pressure is only created by heat expansion and controlled by the vent cap. It's a closed system, not an open system like a well pump filling a vented tank. Centrifugal pumps don't build much of a pressure head because they have too much internal clearance. They are designed only to create flow. Most well pumps aren't true centrifugal anyway, but are high flow turbine pumps that need to be submerged. In a cooling system, the only reason for pressure is to control the boiling point.

I get very wordy when trying to explain because that's the way my mind works, like thinking out loud.

Basically what I'm saying is the flow will be divided between the filter and the bypass hole. Too big a hole will negate the filter.

No you are good about how you worded it...and I understood having done a lot of hydraulic system work myself. Where I goofed myself up is I did not realize he had implemented a bypass aside from the positive flow ports through the housing and filter. If this is the case my advice to drill this bigger is absolutely wrong. I thought the main porting through the housing and filter was going to be restricted to that small hole (as many are on big rigs) which would be a disadvantage in this case and needed to be bigger for more overall flow through the core.

Please nobody butcher me for resurrecting this thread. OP did you ever cut your coolant filter open to find out how it looked? if no response I will start my own thread on this